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      05-28-2009, 10:31 PM   #1
farbarg
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new brake pads and low vibrations

I just had my carbotech XP10's installed. And, as expected, they squeal. That's fine. However, I'm also noticing some low vibrations coming from them as well. Some you can almost feel through the pedals. This is most evident at low speeds and happens intermittently. The dealer says this is from the automatic brake cleaning system applying the brakes to make sure they're dry. In traffic today it was intermittent but happening consistently every 15 seconds or so. Anyone else? Or is there another reason, like, new pads
Thanks.
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      05-28-2009, 11:09 PM   #2
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I'm no expert but I did not experience this with my track set of pads. And the pads are make-shift PFC 01's.

...which are outstanding by the way...
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      05-29-2009, 06:43 AM   #3
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Did you bed them in? They need to remove the stock pad deposits on your rotor and then transfer their own compound before they will work properly. You can verify this with Carbotech.
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      05-29-2009, 01:02 PM   #4
farbarg
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Quote:
Originally Posted by lucid View Post
Did you bed them in? They need to remove the stock pad deposits on your rotor and then transfer their own compound before they will work properly. You can verify this with Carbotech.
The tech said he tried to, but then I repeated the procedure last night. Roughly following carbotech's procedure, I got them warmed up with some lighter stops and then did 7-8 65 to 10 stops, and then drove around a bit to let them cool down. The sound is a bit better today, but still happens.

Seems unlikely anything is fundamentally wrong, so I'm not going to worry about it for the track day tomorrow.

BTW, here's a dumb question. Do the calipers adjust to brake pad wear? Or do they always return to the same resting position? In other words, if I have rubbing, but wear down the pads, will this increase the distance btwn pad and rotor when not braking?

Thanks.
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      05-29-2009, 01:06 PM   #5
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As your pad loses thickness the static piston offset will increase (meaning, the piston will come out and stay out). That is why you need to push the piston back when you put in new pads.
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      05-29-2009, 01:15 PM   #6
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Originally Posted by lucid View Post
As your pad loses thickness the static piston offset will increase (meaning, the piston will come out and stay out). That is why you need to push the piston back when you put in new pads.
So, is that basically the primary adjustment error in installation, that perhaps the piston was not depressed enough when the new pads were put in? I take your response to basically mean that, whatever adjustment error was present at installation will not be remedied by increased brake pad wear.

Thanks again for the info, lucid, I really appreciate it.
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      05-29-2009, 01:39 PM   #7
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One can't really make an error in pushing the piston back during a pad swap because if you haven't pushed the piston back far enough you won't be able to place the new pads in, so it will be a no go from the start. Once the new pads are in and you depress the brake pedal, fluid pressure will push the pistons out and they will make contact with the pads. In other words, I don't see how there can be an installation error if your brakes are working fine apart from this small vibration issue, which will most likely go away once the carbotech compound is fully transferred to your rotors.
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      05-29-2009, 01:54 PM   #8
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Quote:
Originally Posted by lucid View Post
One can't really make an error in pushing the piston back during a pad swap because if you haven't pushed the piston back far enough you won't be able to place the new pads in, so it will be a no go from the start. Once the new pads are in and you depress the brake pedal, fluid pressure will push the pistons out and they will make contact with the pad. In other words, I don't see how there can be an installation error if your brakes are working fine apart from this small vibration issue, which will most likely go away once the carbotech compound is fully transferred to your rotors.
I re-read your DIY on brake installation, went out and checked to make sure all the anti-vibration clips were in, and have to agree. Looking forward to transferring more compound tomorrow.
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      05-29-2009, 02:02 PM   #9
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Quote:
Originally Posted by farbarg View Post
I re-read your DIY on brake installation, went out and checked to make sure all the anti-vibration clips were in, and have to agree. Looking forward to transferring more compound tomorrow.
It might take some time, maybe even a track session. If it is still vibrating after that, you might want to give carbotech a call...
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      05-29-2009, 02:29 PM   #10
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Is 7-8 stope enough?

The new Brembo kit had me do 30 decelerations from 40 to 15 with .5 mi gaps. Approx 3 secs of braking each time.
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      05-29-2009, 03:33 PM   #11
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65mph is not fast enough nor is 8 decelerations enough repetitions. Also you need to concentrate on not applying ANY brake pressure until the rotors cool down or you will develop pad deposits on the rotors. This will apply at the end of a track session, as well.

IMO you should feel some slight loss of brake efficiency over the last few applications. If not, then you didn't get the pads hot enough. I expect to engage the ABS in the process of slowing the car during the final few applications.
I want the entire system to work at the track - might as well test it.

Stoptech's view on bedding in stock sized brake systems.
http://www.stoptech.com/tech_info/wp_bedinstock.shtml
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      05-29-2009, 04:26 PM   #12
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Quote:
Originally Posted by ff1600 View Post
65mph is not fast enough nor is 8 decelerations enough repetitions. Also you need to concentrate on not applying ANY brake pressure until the rotors cool down or you will develop pad deposits on the rotors. This will apply at the end of a track session, as well.

IMO you should feel some slight loss of brake efficiency over the last few applications. If not, then you didn't get the pads hot enough. I expect to engage the ABS in the process of slowing the car during the final few applications.
I want the entire system to work at the track - might as well test it.

Stoptech's view on bedding in stock sized brake systems.
http://www.stoptech.com/tech_info/wp_bedinstock.shtml
Thanks for the pointers. Looks like one should repeat the process 2 or 3 times, and perform up to 10 stops (not 8) per set. I was definitely stopping hard enough to engage the ABS a few times, I could smell them easy enough (though that's probably not a reliable indication of sufficient temperature), and there was some fade at the end. I'll give the process another whirl this evening.
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